-LRB- CNN -RRB- -- NATO officials said Monday they have sent a team to investigate an incident in central Afghanistan where troops thought they were battling militants , but instead may have exchanged gunfire with Afghan police .

The operation , which took place Sunday in Daikundi province , led to the death of three Afghan police officers and wounded three others , the International Security Assistance Force said .

NATO troops were conducting a patrol in a village when they came across nine armed people who were setting up what `` appeared to be an ambush position , '' the force said in a statement .

The service members called in aerial support .

Later , troops determined the air strike may have been carried out against an Afghan police team , the force said .

`` While we take extraordinary precaution while conducting operations to avoid friendly casualties , it appears innocent people may have been mistakenly targeted , '' said U.S. Army Col. Rafael Torres , the director of the force 's Joint Command Combined Joint Operations Center director .

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The operation takes place in Daikundi province

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NATO troops think they have come across men setting up an ambush

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They call in aerial support

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Later , they find the attack may have been carried out against an Afghan police team